Regenerate documentation (#1980)

Resolves #1979 and ensures that the content from #1861 is included in the repository-published documentation.

docs/installation_and_usage.md

@@ -100,11 +100,6 @@ Options:
                                   respect --force-exclude option on some
                                   editors that rely on using stdin.
 
-  --stdin-filename TEXT           The name of the file when passing it through
-                                  stdin. Useful to make sure Black will respect
-                                  --force-exclude option on some editors that
-                                  rely on using stdin.
-
   -q, --quiet                     Don't emit non-error messages to stderr.
                                   Errors are still emitted; silence those with
                                   2>/dev/null.

docs/pyproject_toml.md

@@ -55,9 +55,10 @@ line-length = 88
 target-version = ['py37']
 include = '\.pyi?$'
 exclude = '''
-
-(
-  /(
+# A regex preceded with ^/ will apply only to files and directories
+# in the root of the project.
+^/(
+  (
       \.eggs         # exclude a few common directories in the
     | \.git          # root of the project
     | \.hg